1. Field of the Invention
The present invention relates to an electrical connector for electrically connecting an electronic package such as a land grid array (LGA) chip with a circuit substrate such as a printed circuit board (PCB), and particularly to an electrical connector with improved retention protrusions for conveniently and securely positioning an LGA chip in the electrical connector.
2. Description of the Prior Art
Land grid array (LGA) electrical connectors are widely used in the connector industry for electrically connecting LGA chips to printed circuit boards (PCBs) in personal computers (PCs). Details are provided in xe2x80x9cNonlinear Analysis Helps Design LGA Connectorsxe2x80x9d (Connector Specifier, February 2001, pp. 18-20). Conventionally, one kind of the LGA connector mainly comprises an insulative housing, a multiplicity of terminals received therein, and a load plate and a cam lever pivotably mounting on two opposite sides of the housing. The housing defines a multiplicity of terminal passageways in a rectangular array, for interferentially receiving corresponding terminals. Due to the very high density of the terminal array which an LGA chip may have, the LGA chip needs to be precisely seated on the LGA connector. This is to ensure reliable signal transmission between the terminals and the LGA chip. For example, means for accurately attaching an LGA chip to an LGA connector are disclosed in U.S. Pat. Nos. 4,504,105 and 4,692,790.
Referring to FIG. 5, a conventional LGA connector 6 comprises an insulative housing 60, a multiplicity of terminals 61 received in the housing 60, and a load plate 62 and a cam lever 63 pivotably mounted on two opposite sides of the housing 60. The load plate 62 defines a channel 620 receiving the cam lever 63. To mount an LGA chip (not shown) on the LGA connector 6, the load plate 62 is rotated up until it is perpendicular to the housing 60. The LGA chip is seated in the housing 60, and is loosely engaged with the terminals 61. The load plate 62 is rotated down so that it rests on the LGA chip. The cam lever 63 is rotated down until it engages in the channel 620 of the load plate 62. When the cam lever 63 has reached the end of its travel, the load plate 62 presses the LGA chip into firm engagement with the terminals 61 of the connector 6.
In the above-described assembly process, the load plate 62 presses the LGA chip between two opposite sides of the housing 60 of the connector 6. Generally, a material of the housing 60 is not resilient, and the sides of the housing 60 can not elastically deform under pressure from the LGA chip. If the LGA chip is narrower than a distance between the opposite sides of the housing 60, the LGA chip may be poorly positioned relative to the terminals 61. This can adversely affect mechanical and electrical connection between the LGA chip and the connector 6. If the LGA chip is wider than a distance between the opposite sides of the housing 60, the housing 60 is liable to break. Furthermore, when the load plate 62 presses the LGA chip to firmly engage with the terminals 61, the housing 60 is liable to break if asymmetrical force is inadvertently applied thereto.
FIG. 6 shows another conventional LGA connector 6xe2x80x2 devised to overcome the above-described problem. The connector 6xe2x80x2 comprises an insulative housing 60xe2x80x2, and a multiplicity of terminals 61xe2x80x2 received therein. In forming the connector 6xe2x80x2, a carrier strip (not shown) is used. The carrier strip comprises a row of the terminals 61xe2x80x2, and a row of connecting sections (not shown) respectively connecting the terminals 61xe2x80x2 with a main body of the carrier strip. The housing 60xe2x80x2 comprises four raised sidewalls 62xe2x80x2, and a flat base 63xe2x80x2 disposed between the sidewalls 62xe2x80x2. The base 63xe2x80x2 and the sidewalls 62xe2x80x2 cooperatively define a space therebetween for receiving an LGA chip (not shown) therein. The base 63xe2x80x2 defines a multiplicity of terminal passageways 64xe2x80x2 for receiving the terminals 61xe2x80x2 therein. When the LGA chip is seated on the LGA connector 6xe2x80x2, the four sidewalls 62xe2x80x2 can securely engage the LGA chip therebetween.
However, installation of terminals 61xe2x80x2 into those passageways 64 near two of the sidewalls 62xe2x80x2 is problematic. Once the terminals 61xe2x80x2 have been inserted into such passageways 64xe2x80x2, the connecting sections of the carrier strip must be cut from their corresponding terminals 61xe2x80x2. Because the carrier strip is located close to the relevant sidewall 62xe2x80x2, there is insufficient space to manipulate the carrier strip to allow easy cutting off of the connecting sections. Such manipulation is blocked by the sidewall 62, which is liable to sustain damage as a result.
Therefore, a new LGA electrical connector which overcomes the above-mentioned problems is desired.
An object of the present invention is to provide an electrical connector for electrically connecting an electronic package such as a land grid array (LGA) chip with a circuit substrate such as a printed circuit board (PCB), whereby the electrical connector can quickly and conveniently guide the LGA chip into its correct position.
Another object of the present invention is to provide an electrical connector having means for accurately positioning an electronic package such as an LGA chip thereon, whereby manufacturing and transportation costs of the electrical connector are reduced.
To achieve the above objects, an electrical connector in accordance with a preferred embodiment of the present invention is for connecting an LGA chip with a PCB. The connector includes an insulative housing, a frame engaged with the housing, and a plurality of terminals received in the housing. The housing defines four sides. A plurality of arcuate protrusions is formed on two adjacent of the sides. The frame has four sidewalls defining a central cavity therebetween for receiving the LGA chip therein. Two adjacent of the sidewalls define a plurality of cutouts in respective inner faces thereof, corresponding to the protrusions respectively. The frame is mounted on the housing, with the protrusions being engagingly received in the corresponding cutouts. When the LGA chip is engaged with the connector, the protrusions elastically deform to accurately guide and securely fix the LGA chip in the connector.